Office building



FIG. 1 is a front elevational view of an office building showing my new design;

FIG. 2 is a rear elevational view;

FIG. 3 is a left side elevational view;

FIG. 4 is a right side elevational view; and

FIG. 5 is a top plan view. 

The ornamental design for an office building, substantially as shown and described. 